Speed control mechanism



Feb. 26, 1946', c. R. ALDI-:N

SPEED CONTROL MECHANISM 2 Sheets-Sheet 1 Filed Feb. 4, 1945 w www Feb. Y26, 1946. R, ALBEN 2,395,101

SPEED CONTROL MECHANISM Filed Feb. 4, 1943 2 Sheets-Sheet 2 F1- 4 n /1 d/644 v/7lof@6.

Patented Feb. 26, 1946 SflmiE1sr PATENT OFFICE- SPEED oN'rnoL MEcHaNlsiu Carroll R. Alden, Detroit, Mich., assigner to Exl- Cell-Q'Corporaton, Detroit, a corporation of Michigan A' Application February 4, 1943, Serial No. 474,702 1,6V Claims. (Cl. 290-40) mention relates, i@ a speedoeirol mesh,- anq Materne@ primarily wiihihe aviopossible to 'ascertain whether 4the -station frequeny'is above or below the required frequency for loks no ated on' the system." Any adjustis accomplished 'byn remote alteration of the engine or turbine v`governors' under vthe control of one br more operators depending upon the size of the station. No satisfactory automatic regulating device has yet been developed for large central stations.

1n communities which are served by relatively small stations, it is' just :as important toiegulate'station frequency for vlthe same' purpose,` but manual adjustm'er'it is economically unsound uin relation to the output of the station. The continuous, automaticregulaton of the small stia'.- tion frequency has" therefore b'een a serious problem. The usersof electric current in such locations are also users of motor driven clocks, but an electrical system in which the clocks gain time when the station frequency is above standard and which lose time when the frequency is'below standard is obviously not a satisfactory arrngemnt.

1t' is therefore the principal object of my invention to provide a speed control mechanism which automatically 'and continuously regulates vwith acceptable accuracy the speed of a prime mover hence the frequency of a connected @mting (urfen gpeato This and further objects of my invention will be set forth ,in .the following specification, reference being had to the accompanying drawings, and the novel means by which said objectsare eiectuated will be denitly'pointed out in the claims.

In the drawings:

Figure 1 is a longitudinal, sectional elevation ofthe metering pu'mp of an oil burning engine fovrr'ning .partv of'r engine-generator' set and showing my improved speed control applied thereto.

Figs. 2 and 3 are views looking in the direction ofthe arrows '2 and'3', respectively,- in Fig; -1 sho-wing certain details'of 'the control. n

Fig. '4 is a'longitudinal, sectional elevation of a differential mechanism forming part ofthe control. t i

' Figi 5 is a section along the line 5-5 in Fig. 4. Fig. 6 is a diagram of thefele'ctridal circuit-in- Fig'. '7 is an enlarged fragmentary sectional elevation of the left end" of the mechanism illustrated in Fig. 4 showing the meansA for resettingV the mechanism.

My improved speed control will he described in connection with an oil burning engine'which is connected to` a generator V(not shown)` whose frequency is' adjusted to "a standard" speed'by controlling the' speed of the engine within narrow limits". It Willbe understood, however', that thegener'i'c aspects of theinvention are directed tov any'type ofprime'mover.' i

Referring to Figs, 1-3, inclusive, the numeral IU designates the housing of the metering'pump ofV an oi1 burning engine (not shown) having journaled therein a sleeve shaft "I I voncne 'end of whichis secured a gear I2 that maybe Idriven from any convenient part of the engine. Also secured'to the shaft II isa vswa's lfplate` I3 which providlsfreciprocating movement' for a plurality actuating rods `I4 warfare Sudabiy mounted in the housing IG and'ofwhich there isr one for each engine cylinder; Eachrv rod I4 actuates a pump plunger Iinfa discharging direction, i; e.,

tow'a'rd lthe ieft'as'viewed'inrig. 1, and return strokes of the plungerare accomplished by a helical spring I6 which encrcles the p1unger,`one end'abutt'ing against a convenient portion of the housing 'I0' and the oppositeend against a fiance I1 'secured tothe i'end of the piunger'a'nd against which the rod I4 bears. During-discharge movements of theplungr 15, oil that has accumulated Within the pumpchamber I8 is forced through a ball' check valve i9 into a fuel line 2|) leading to one of the 'engine cylinders. Controlover the amountof fuel 'discharged to each' engine 'cylinder 'is'exercised by a vvalve 2I which' is rotarily and reciprocably mounted' in a "bore `22`in the housing vI 0 that is coaxial with theshaft `I I.` The rightend' of the valve is drivably connected to one end of a coupler 231whose'opposite end has a driving `connection with the 'splined end 0f 'a shaft 2 4' which is journale'd within the sleeve shaft 11| and 'driven thereby: The' intermediate portion of the valve 2| is reduced in diameter to provide an annular belt 25 which is only interrupted by a longitudinally extending tapered land 26. The belt is always in communication with an annular groove 21 formed in the bore 22 and to which fuel is supplied through a passage 26 in the housing which communicates with a pipe 28 that may be connected to any convenient source of fuel supply such as a pump (not shown). Communication between the chamber i8 and the belt 25 is eiected by a port 33 and the amount of the fuel delivered to the chamber depends upon the axial position of the land 25 with respect to the port. Oil at constant pressure is always present in the belt 25 and hence as the valve 2| is moved tcward the right more fuel will be dis-charged by the plunger |5 into the line 2Q, and the contrary condition will exist when the valve is moved in the opposite direction.

It will be understood that the valve 2| operates in timed relation to the several plungers i5 and axial shifts of the valve toward the left, i. e., in the direction which decreases the amount of fuel delivered to each cylinder, is accomplished by a rod 3l which extends coaxially through the shaft 24, the left end of the rod being received within and abutting a wall on the coupler 23, while the right end extends beyond the shaft 24 for engagement with the ends of a plurality or weighted levers 32 each of which is pivotally mounted on the gear I2. The Valve 2| is urged in the opposite direction by a helical spring 33 whose right en`d is received within a bore 34 in the housing |0 coaxial with the bore 22 and within which is slidably mounted an abutment 35 against which the right end of the spring bears. An extension 36 projecting from the left end of the valve 2| bears against the abutment 35 and the spring 33 is adjustably loaded by means of a follower 31 slidable within a sleeve 38 that is threaded in the housing I0. The follower 31 iS contacted by an adjusting screw 39 whereby the follower may be shifted to any desired position depending upon the loading to be applied to the spring 33 and this screw is threaded in a bushing 4o which in turn is threaded in the sleeve 38. The adjusted position of the screw 39 may be secured by a look nut 4 So far as described, the structure is substantially identical with the metering pump disclosed in my United States Letters Patent 2,156,933, and in this connection it will be understood that the spring 33 may be manually adjusted to secure any desired standard speed of the engine at some predetermined load, and therefore constitutes the primary control feature of my improved mechanism. However, in view of the fact that the control is intended to automatically maintain the standard speed of the engine despite variations in the load so that the frequency of a driven generator can be controlled within sutil ciently narrow limits to enable electric clocks to be floated on the generator system, it is necessary to provide secondary means which are automatically operable to restore the standard speed of the engine in the event of changes in the engine load. The mechanism for accomplishing this result will now be described.

Referring to the same gures, one end of a rock arm 42 is secured by a pin 43 to the reduced end of bushing 40, this end of the arm being clamped between the bushing and the lock nut 4|. The opposite end of the arm 42 is rounded along its opposite edges to form a bulbous nose 44 which is received within a slot 45 provided in a lever 46 having an intermediate lug 41 that is pivotally secured by a pin 48 to the underside of a plate 49 that is attached to the pump housing |0. The lever 46 also includes laterally and oppositely extending arms 50 and 5| which are disposed on opposite sides of the nose 44. A solenoid 52 is secured to the underside of the plate 49 and one end of its core 53 contacts a headed screw 54 which is threaded through the arm 53 and may be adjusted in any desired position by a lock nut 55. A solenoid 56 is also secured to the underside of the plate 49 and one end of its core 51 contacts a headed screw 58 that is threaded through the arm 5I and whose adjusted position may be locked by a nut 59.

As illustrated in Fig. 3, the solenoid cores 53 and 51 are shown in retracted position, i. e., no current flowing through either solenoid and the lever 46 is centralized in the position illustrated by means of a pair of balancing springs 60, each of which is mounted in the casing 6| secured to the plate 49, one end of the casing being closed and the opposite end being open to receive a plunger 62 against which the spring 60 bears. As indicated in Fig. 3, the plunger 62 bears against the end of the arm 50, and a similar plunger against the end of the arm 5|.

From the foregoing, it will be understood that if the lever 46 is rocked in a counterclockwise direction by the solenoid core 53, as viewed in Fig. 3, the rock arm 42 will be rotated in a clockwise direction, as viewed in Fig. 2, and will therefore move the follower' 31 toward the right and increase the loadingT (n the spring 33, thus shifting the valve 2l toward the right and increasing the speed of engine operation. On the other hand, if the lever 46 is rocked in a clockwise direction by the solenoid core 51, as viewed in Fig. 3, the rock arm 42 will be rotated in a counterclockwise direction as viewed in Fig. 2, to thereby unload the spring 33 and permit a shifting of the rotary valve 2| toward the left under the impulse of the weighted levers 32 to thereby decrease the speed `i of engine operation, Ordinarily, the above conditions will occur, respectively, when the load is increased and decreased on the engine resulting in a corresponding decrease and increase, respectively, in the engine speed.

In Figs. 4 to 6, inclusive, there is illustrated a mechanism whereby diierences in speed between the engine and the standard speed, and therefore differences between the generator frequency and the standard frequency are indicated. These differences require repositionings of the valve 2| in the proper direction to restore the standard engine speed. rllhe standard speed may be oltained from an independently driven master clock 63 or any regulator or other device operating at a constant speed, while the speed of the engine is indicated by a synchronous motor driven clock 64 that may be connected by wires 65 to the circuit supplied by the generator. A pinion 66 is driven by the clock 64 and meshes with a gear 61 secured to a sleeve shaft G8 that is journaled in a bearing 69 forming part of a casing 10. The shaft 68 extends within a conipartment 1I provided in the casing and is formed as an internal gear 12 forming part oi a planetary differential mechanism 13. The standard speed clock 63 drives a shaft 14 that extends through and is journaled in the sleeve shaft 63 and has secured to the end thereof within the compartment 1| a sun gear 15. A pair of planetary gears 16, diametrically related on opposite sides of the sun gear T, mesh therewith and with the inf. ternal gear 12 and each is rotatable on a `stub shaft 11 that is carried by a disc Iii.

It` will be evident that the sun gear 15; con-` stitutes one arm of the differential gear, the internal gearl 1.12 constitutes a second arm, while the disc 118 forms. a third arm. Accordingly, so. long as the clocks G3 and 64 arelcharacterized by the same speed, the planet gears 16 will simply rotate on their respective stuby shafts without, effecting any rotary movement `of the disc u. However, if a speed difference exists ybetween the clocks 63 and '64, such dinerencewill cumulatively appear as a rotary movement of theA disc 118 ,and the direction thereof will depend upon whether the speed of the clock 63 is lower or higher than that of the clock 64.

The disc 18- is secured to one end of a shaft 19 that is journaled in and extends through a `wall 8a which separates a` second compartmentgl from the compartment 1l. Within the former compartment a disc 82 is secured to the yshaft 19 and a portion of its periphery is recessed as at 83 and the terminals of this recess are dened by shoulders 84 and 85. Normally received within this recess is a nose 86 forming part of a rocker 81 which is pivotally mounted on the wall 80 by a pin 88 and below the pin 88, rthe rocker carries a pair kof mercury switches 89 and 99. One electrode of the switch 89 is oon-- nected by a wire 9| to one end of the solenoid 52, while the opposite end of the solenoid is vconnected by a wire 92 Ito a line wire 93 which may be connected in the generator circuit or to any independent source of electrical supply. The other electrode of the switch 89 is connected by a wire 94 to a line wire 95. One electrode of the switch 90 is connected by a wire 96 to the line wire 95, and the other electrode of the same switch is connected by a wire 91 to one end of the solenoid 5B whose opposite end is connected by a wire 98 to the line wire 93. Normally the disc B2 and rocker 81 occuppy the positions illus, trated in Fig. 5, i. e., lwith the nose 85 extend,- ing within the recess 83 and between the shoul: ders B4 and 85 and in this position the switches 89 and 90 are open.

In describing the operation of my improved control, it will be necessary to make certain assumptions regarding the operating conditions since the latter are capable of many variations. For present purposes, it will be assumed that the governor spring 33 has been primarily adjusted by the screw 39 so that when `the engine is onehalf loaded the 'generator connected thereto is capable of maintaining the desired frequency or in other words the engine runs at standard speed. Now, ir" a full load is applied to the engine, it will be obvious that, unless some compensation is interposed, the engine would slow down so that the generator would operate with a lower frequency than the desired frequency, As a further assumption, it will be considered that under these conditions the engine would run at two per cen-t below the standard speed so that electric clocks floated on the generator supply circuit would lose time at the rate of one second in every -fty seconds of elapsed time. It will further be assumed that the recess notches 84 and 85 are so spaced with reference to the illustrated mid-position of the rocker nose 86 that a loss in time of two seconds as indicated by the synchronous clock 64 would cause a rotation of the disc 82 through an arc sufficient to engage the shoulder 8 4 with the nose 86 and so rotate the rocker 81 suflithis loss. will have to continue for one. hundred seconds of elapsed time before` the switch will tripA to increase the frequency and stop the loss.

fit is now assumed that, with the governor adjustment compensated as above described,4 the speed of the prime mover is increased to a point appreciably `more than just suiiicient to reestablish standard speed and specically a gain infrequency of two per cent under the full loaded condition, the speed difference thereby exhibited kbetween the clocks 63 and 64 will appear as a rotary movement of the disc 82 in the opposite direction. This action will cause switch 89 to. open 4and close at intervals and will therefore keep the switch on the edge of closure.

If with the parts in the positions just described, the load on the engine should drop to a value which withthe given adjustment of the primary adjusting screw 3.9 causes a gain of two per cent in frequency, the rocker 86 will not be rotated to a position closing the switch 90 until the disc 82 has been rotated through an arc sufiicient to engage the recessed shoulder with the rocker nose 86, The time required for this correction under the assumed conditions will be four seconds'of differential clock time, i. e., two seconds on each side of the central position of the rocker as illustrated in Fig. 5. At the assumed rate of two per cent gain in speed, the time involved will be two hundred seconds of elapsed time before the soienoid 5E is energized to permit an unloading of the governor' spring 33 and a shift of the rotary valve toward the left to decrease the governed speed of the engine,

From the foregoing it will be understood that my improved control enables `the engine speed and therefore the generator frequency lto be regulated within very narrow limits, specifically one in which it is possible to enable standard house-` hold clocks to be floated on the generator system and to be operated with an acceptable degree of accuracy. K v

It will be further understood that the portion of the control illustrated in Figs. 4 to 6, inclusive, can be utilized to control a plurality of governors f as illustrated in Fig, l, which may be associated with several engines which have their connected generators in parallel on a given system or in a given station. Moreover, it is evident that while in the specii/ic example described two contactors or switches 89 and 90 are employed for increasing and decreasing, respectively, the speed of the prime mover, the control is capable of operation with only one switch. For example, if the primary adjusting screw 39 was arranged to allow a. constant loss in the engine speed a singlev switch could be used to so compensate the governor adjustment as to provide for a predetermined rate of gain until the accumulated loss of di'iferential clock time had been absorbed, or if the screw 39 allowed a constant gain in the engine speed, a single switch could be used to provide for a predetermined rate of loss in such speed until the appropriate time had been absorbed.

vIn a control of the foregoing character, it is desirable to provide a signal means whereby the operator may be warned of any derangement to the engine before uncontrolled differences between the generator and standard frequencies result in perceptible inaccuracies in clocks floated on the system. In the present instance, this situation is controlled by an arcuate lever 99 which adjacent its upper end (see Figs. 4 and 7) is provided with a slot |00 through which extends a pin |0| that is mounted in a wall of the compartment 8| whereby the lever 99 is arranged for a combination pivoting and sliding movement. The lower end of the lever is formed as a nose |02 which under normal conditions, i. e., with the disc 82 in the position illustrated in Fig. 5, or in either of its limit control positions in which the shoulders 84 and 85 engage the nose 8G bears against a flank of this disc adjacent the periphery thereof and this position is maintained by means of a spring |03 one end of which is secured to the lever and the opposite end to the wall 80. The lever 99 carries a mercury switch |04 one electrode of which is connected by a wire |05 with the line wire 93 and the other electrode is connected by a wire |05 with a lamp |01 which in turn is connected by a wire |03 to the line wire 95. It will be understood that the lamp l0'! is generally indicative of any type of signal means that is capable of giving visual or audible warnings in the normal operation of the device.

The lever 99 occupies the position illustrated in Fig. 4 which is one in which the mercury switch |04 is open, and this condition is maintained so long as the engine operates under the control 1".

above described. However, if for any reason a speed difference should exist between the clocks 63 and 64 for a time sufficient to rotate the disc 82 through an angle of 180 degrees, then the spring |03 will shift the lever 99 to the position illustrated in Fig. 7. This action is permitted by reason of the fact that the lever nose |02 enters the recess B3 in its then displaced position. This shift of the lever 99 will accordingly close the mercury switch |04 and operate the signal |01. After the difficulty in the engine has been corrected and assuming that the lever 99 is occupying the position illustrated in Fig. 7, the latter can be returned to the original position shown in Fig. 4 by means of a plunger |09 y slidabiy mounted through the top wall of the compartment 8|. The lower end of this plunger may be appropriately shaped to t the top edge of the lever 99 so that when the plunger is moved downward the lever will be rocked to the position shown in Fig. 4 thus opening the switch |04. Thereafter, the disc 82 may be appropriately rotated until the recess 83 thereof is properly related to the rocker 8'! as illustrated in Fig, 5.

I claim as my invention:

l. In mechanism for regulating the frequency of a generator subject to varying loads by adjusting its speed to achieve an average speed substantially equal to a reference speed, the generator being driven by a prime mover under the control of a governor loaded by a spring adjusted to substantially maintain the reference speed at a predetermined load, master speed means providing the reference speed, means operating in synchronism with the generator, means responsive to unidirectional speed differences between the reference speed and synchronous means, and means for varying the adjustment of the spring to compensate for departures from the reference speed comprising an adjustable member engageable with the spring, and an electric circuit including switch means having a lost motion operating connection with said responsive means and being open during periods of a predetermined limiting speed difference and closed by the responsive means when the difference is exceeded and a solenoid having a core for controlling the movement of the member.

2. In mechanism for regulating the frequency of a generator subject to varying loads by adjusting its speed to achieve an average speed substantially equal to a reference speed, the generator being driven by a prime mover under the control of a governor loaded by a spring adjusted to substantially maintain the reference speed at a predetermined load, master speed means providing the reference speed, means operating in synchronism with the generator, diierential gear means, the first and second arms of the gear being driven by the master speed and synchronous means, respectively, and means for varying the adjustment of the spring to alter the engine speed by compensating for departures from the reference speed comprising an adjustable member engageable with the spring, an electric circuit including switch means open during periods of a predetermined limiting speed difference and a solenoid having a core for controlling the movement of the member, and a trip driven by the third arm of the gear means for closing the switch means when the difference is exceeded.

3. In mechanism for regulating the frequency of a generator subject to varying loads by adjusting its speed to achieve an average speed substantially equal to a reference speed, the generator being driven by a prime mover under the control of a governor loaded by a spring adjusted to substantially maintain the reference speed at a predetermined load, master speed means providing the reference speed, means operating in synchronism with' the generator, differential gear means, the first and second arms of the gear being driven by the master speed and synchronous means, respectively, and means for varying the adjustment of the spring to alter the engine speed by compensating for departures from the reference speed comprising an adjustable member engageable with the spring, an electric circuit having a pair of parallel branches each including switch means open during periods of a predetermined limiting speed difference above and below the reference speed and a solenoid having a core for controlling the movement of the member, and a trip driven by the third arm of the gear means for closing the switch means, respectively, when the difference is exceeded in either direction.

4. Mechanism for regulating the frequency of a generator subject to varying loads by adjusting its speed to achieve an average speed substantially equal to a reference speed, the generator being driven by a prime mover under the control of a governor, comprising primary means adjustably related to the governor and set to substantially maintain the reference speed at a predetermined load, master speed means providing the reference speed, means operating in synchronism with the generator, means responsive to speed differences between the reference speed and synchronous means including a member movable in either of two directions through a predetermined range dependent upon Whether the reference speed is higher or lower than the speed of the synchronous means, and secondary means adjustive to the governor and controlled by the member after a predetermined movement thereof in either direction beyond said range for altering th'e prime mover speed.

5. Mechanism for `regulating the frequency of a generator subject to varying loads by adjusting its speed to achieve an average speed substantially equal to a reference speed, the generator being driven by a prime mover under the control of a governor, comprising primary means adjustably related to the governor and set to substantially maintain the reference speed at a prede termined load, master speed means providing the `reference speed, means operating in synchronism with the generator, means responsive to speed differences between the reference speed and synchronous means including a member movable in either of two directions dependent upon whether the reference speed is higher or lower than the speed of the synchronous means, and secondary means adjustive to the governor and controlled by the member after a predetermined movement thereof in either direction for altering the prime mover speed, the adjusting element f the primary means being carried by the directly adjusting element of the secondary means.

6. Mechanism for regulating the frequency of an engine driven generator subject to varying loads by adjusting its speed to achieve an average speed substantially equal to a reference speed, comprising throttle means for the engine, a spring and a centrifugal governor mutually acting to position the throttle meansprimary means loading the spring to maintain the throttle means in substantially a reference speed position at a predetermined .load on the engine, master speed means providing the reference speed, means operating in synchronism with the generator, means responsive tospeedfdiiierences between the reference speed and synchronous means including a member movable in either of two directions dependent upon whether the reference speed is higher or lower than th'e speed of the synchronous means, and secondary means adjustive to the spring and controlled by the member after a predetermined movement thereof in either direction for altering the engine speed.

7. Mechanism for regulating the frequency of an engine driven .generator subject to varying loads by adjusting its speed toachieve an average speed substantially equal to aA yreference speed, comprising throttle means for the engine, a spring and a centrifugaligovernor mutually acting to position the throttle means, a primary screw adjustable to load the spring to maintain the throttle means in substantially'a reference speed position at a predetermined load on the fengine, t,

master speed means rproviding the reference speedyineans operating in synchronism with the generator, means'responsive to speed diierences between the `reference speed and synchronous means including a member movablein either of two directions dependent upon whether the reference spee'dris higher or lower than'the speed of the synchronous means, anda secondary screw adjustive to the spring and controlled by the member after 'a predetermined movement thereof in either direction for altering the engine speed.

8. Mechanism for regulating the frequency of an engine driven generator subject to varying loads by adjusting its speed to achieve an average speed substantially equal to a reference speed, comprising throttle means for the engine, a spring and a centrifugal governor mutually acting to position the throttle means, a primary screw adjustable to load the spring to maintain the throttle means in substantially a reference speed position ata predetermined load on the engine, master speedr means providing the reference speed, means operating in synchronism with the generator, means responsive to speed differences between lthe reference speed and synchronous means including a member movable in either of two directions dependent upon whether the reference speed is lhigher orlower than the speed of the synchronous means, and a secondary screw adjustive to the spring and controlled by the member after a .predetermined movement thereof in either direction for altering the engine speed, .the pri-mary screw being threaded through the secondary screw.

9. Mechanism for regulating the frequency of an engine driven generator subject to varying loadsfby adjusting its speed to achieve an average speed substantially equal to a reference speed, comprising throttle means for theeng-inaaspring and a centrifugal governor mutually actingy to position the throttle means, a primary screw adjustable to load the spring to maintain the .throttleineans in substantially a reference speed position at ya predetermined load on the engine, master speed means providing the reference speed, means operating in synchronism with the generator, means responsive to speed differencesbetween the reference speedand synchronous means including -a member movable in either of two directions dependent upon whether the reference speed is :higher or lower thanfthe speed of thel synchronous means, and'a secondary screw-adjustive to the spring and controlled by the ymember .after `a predetermined movement thereofin either direction for altering the engine speed, the primary screw being connected to and extending beyond rthe secondary screw in operative relation tothe spring.

10. Mechanism Afor regulating the frequency of an engine driven generator` subject to varying loads-by adjusting its speed to achieve an average `speed substantially equal to a reference speed,

comprising Ithrottle means for vthe engine, ya.

spring and a centrifugal governor mutually act-r in'g to position the throttle means, primary means loading the spring to maintain the throttle means in .substantially v`a reference speed position ata ypredetermined load on thefengine, master speed means providing the reference speed, means `operating insynchronism with the generator, means `responsive to speed differences between the reference speed .and synchronous :means -due to an increase or vdecrease in enginelspeed relative to the reference speed, yand secondary means controlled bythe responsive means .and arranged to Aindependently vary the loading on ythespring to alter theengine speed when a predetermined speed diiierence is exceeded in-either direction.

ll. Mechanism for regulating the frequency of :an engine driven generator subject to varying loadsbyadjusting its speed to achieve'an average speed substantially 'equalrtoa reference speed, comprising 'throttle ymeans 'for the engine, a.

' spring and afcentrifugal governor mutually .acting toiposi-tionithe .throttle means,;prlmary means loading the: springl to maintain .the throttlemeans 'in substantially a reference speed position at a pre'determine'cliloadon theengine, master speed means providing the reference speed, means operating in synchronism with the generator, means responsive to unidirectional speed differences between the master speed and synchronous means, and secondary means for varying the loading of the spring to alter the engine speed by compensating for departures from the reference speed comprising an electric circuit including switch means open during periods of a predetermined limiting speed difference and closed by the responsive means when the difference is exceeded and a solenoid having a core actuatingly related to the spring.

l2. Mechanism for regulating the frequency oi an engine driven generator subject to varying loads by adjusting its speed to achieve an average speed substantially equal to a reference speed, comprising throttle means for the engine, a spring and a centrifugal governor mutually acting to position the throttle means, primary means loading the spring to maintain the throttle means in substantially a reference speed position at a predetermined load on the engine, master speed means providing the reference speed, means operating in synchronism with the generator, means responsive to Speed differences between the reference speed and synchronous means due to an increase or decrease in engine speed relative to the reference speed, and secondary means controlled by the responsive means for varying the loading of the spring to alter the engine speed by compensating for departures from the reference speed comprising an electric circuit having a pair of Parallel branches each including switch means open during periods of a predetermined limiting speed diierence above and below the reference speed and a solenoid having a core actuatingly related to the spring, the switch means closing, respectively, when the difference is exceeded in either direction.

13. Mechanism for regulating the frequency of an engine driven generator subject to varying loads by adjusting its speed to achieve an average speed substantially equal to a reference speed, comprising throttle means for the engine, a spring and a centrifugal governor mutually acting to position the throttle means, primary means loading the spring to maintain the throttle means in substantially a reference speed position at a predetermined load on the engine, master speed means providing the reference speed, means operating in synchronism with the generator, differential gear means, the iirst and second arms of the gear being driven by the master speed and synchronous means, respectively, and secondary means for varying the adjustment of the spring to alter the engine speed by compensating for departures from the reerence speed comprising an adjustable member engageable with the spring, an electric circuit including switch means open during periods of a predetermined limiting speed difference and a solenoid having a core actuatingly related to the member, and a trip driven by the third arm of the gear means for closing the switch means when the difference is exceeded.

14. Mechanism for regulating the frequency of an engine driven generator subject to varying loads by adjusting its speed to achieve an average speed substantially equal to a reference speed, comprising throttle means for the engine, a spring and a centrifugal governor mutually acting to position the throttle means, primary means loading the spring to maintain the throttle means in substantially a reference speed position at a predetermined load on the engine, master speed means providing the reference speed, means operating in synchronism with the generator, diilerential gear means, the rst and second arms of the gear being driven by the master speed and synchronous means, respectively, and secondary means for varying the adjustment of the spring to alter the engine speed by compensating for departures from the reference speed comprising an adjustable member engageable with the spring, an electric circuit having a pair of parallel branches each including switch means open during periods of a predetermined limiting speed difference above and below the reference speed and a solenoid having a core actuatingly related to the member, and a trip driven by the third arm of the gear means for closing the switch means, respectively, when the diierence is exceeded in either direction.

l5. Mechanism for regulating the frequency of a prime mover driven generator subject to varying loads by adjusting its speed to achieve an average speed substantially equal to a reference speed, the prime mover being controlled by a governor set to substantially maintain the reference speed at a predetermined load, comprising master speed means providing the reference speed, means operating in synchrcnism with the generator, means responsive to speed differences between the reference speed and synchronous means including a member movable in either of two directions dependent upon whether the reference speed is higher or lower than the speed of the synchronous means, means adjustive to the governor and controlled by the member after a predetermined movement thereof in either direction for altering the prime mover speed, and signal means responsive to a predetermined movement of the member in excess of the Iirst named movement.

16, In mechanism for regulating the frequency of a generator subject to varying loads by adjusting its speed to achieve an average speed substantially equal to a reference speed, the generator being driven by a prime mover under the control of a governor loaded by a spring adjusted to substantially maintain the reference speed at a predetermined load, master speed means providing the reference speed, means operating in synchronism with the generator, means responsive to speed differences between the reference speed and synchronous means, and means for varying the adjustment of the spring to compensate for departures from the reference speed comprising an adjustable member engageabie with the spring, and an electric circuit including switch means open during periods of a predetermined limiting speed diiference and closed by the responsive means when the difference is exceeded and a solenoid having a core for controlling the movement of the member and a second electric circuit in parallel with the first circuit including signal means and a switch closed by the responsive means upon the occurrence of a speed diiierence in excess of the first named diiierence.

CARROLL R. ALDEN. 

